Molecular dynamics simulations of Na+-Cl− ion-pair in supercritical methanol

Structural and Dynamical Properties of Alkaline Earth Metal Halides in Supercritical Water: Effect of Ion Size and Concentration

“…As a result, CIPs, SAIPs, and SSIPs are more stable in supercritical conditions compared to those in ambient conditions. This has been previously observed in ion pair association studies by several authors. ,, Because the decrease in the dielectric constant facilitates ion association, one may expect the contact ion pair to be more stable in the 5.55 m solution in supercritical conditions, but in reality, we observe the opposite. There is hardly any decrease in the dielectric constants as we go from the 0.27 m (∼3.47) to 5.55 m solution (∼3.30) in the supercritical conditions.…”

“…For the Cl − ion, the anion−oxygen peak is centered at 0.33 nm, which is in good agreement with that deduced from MD simulations 5,6,28,29,78,81 and from X-ray diffraction studies. The first peaks of the Cl − −O (H 2 O) radial distribution functions are centered at around 0.33 nm in both the thermodynamic states under study.…”

“…The positions of the peak maxima of the ion-solvent radial distribution functions are in good agreement with those reported previously by other authors. 27,28,41,55 From Figures S8a,b−S11a,b, we note that the ion-water structure is markedly dependent on the salt concentration in both ambient and supercritical conditions. The heights of the RDFs for these pairs decrease as the salt concentration increases.…”

“…In recent years, there have been several experimental and theoretical studies on the solvation structure and dynamics of alkali metal halides in SCW, but detailed studies of alkaline earth metal halides in high-temperature, high-pressure systems are rare. Several studies have been reported on the effect of solvent composition on the ion–ion (both alkali and alkaline earth metal halides) potentials of mean force (PMFs) in supercritical conditions via a constrained method (infinite dilution). − It has been established that the contact ion pair (CIP) is the most stable structure in supercritical conditions as compared to that in ambient conditions. However, solvation in a concentrated salt solution may proceed in a different manner than in dilute solutions because the solutes may be present as ion clusters rather than as single ions.…”

Uranyl Arsenate Complexes in Aqueous Solution: Insights from First-Principles Molecular Dynamics Simulations

“…A number of sampling methods have been also developed to compute reaction free energies. For example, the constrained MD method has been validated in various systems to calculate dissociation free energy. ,,,− The FPMD-based vertical energy gap method has been extensively applied to estimate the acidity constants of both organic and inorganic systems covering main group and transition metal elements. − …”